Turbidites


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Related to Turbidites: turbidity currents

Turbidites

 

deposits from turbidity currents on the floor of the seas and oceans, consisting of clastic sediments of various sizes and different degrees of roundness.

The periodic deposition of sediments from turbidity currents on the sea floor disrupts the usual process of sedimentation and produces a series of cycles in sea-floor sediments; the boundaries of the cycles are usually distinct, and the thicknesses vary (usually a few tenths of a centimeter, less often fractions of a centimeter to several meters). In the lower part of each cycle the most coarsely grained sediments grade upward into more finely grained sediments, resulting in graded bedding. The cycle is completed by a thinner layer of argillaceous or carbonate pelitic sediment.

Different slope steepnesses, transport times, and degrees of turbidity-current loading or liquidity cause differences in the structure of turbidites. The remains of shallow-water and littoral organisms transported by a turbidity current are found in the deep-water sediment. The volcanogenic material tephra is sometimes present in turbidites; such sediments are called tephroturbidites. In mineral form they are known as tuff turbidites. Turbidites are widespread among recent and ancient deposits of various ages, especially among sediments in seismically active areas.

L. N. BOTVINKINA

References in periodicals archive ?
The late Cretaceous turbidites in the Mughal Kot Section, Sulaiman Range has been observed, studied, measured and sampled.
Turbidites have less frequently been reported from areas of high sediment supply, such as subaqueous river mouths during flooding where turbidity currents are initiated solely by gravitational failure (Chan & Dott 1983; Heller & Dickinson 1985; Guyard et al.
Sparse fossil age control suggests that thin-bedded ("pinstriped"), well-graded silt-mud turbidites of the Waterville Formation are of Llandovery age and therefore at least partially temporally equivalent to the coarser grained, thicker bedded Sangerville Formation (Pankiwskyj et al.
In 2007 a project was started to work with DZ in Northern Venezuela, sampling Cretaceous Passive Margin and Tertiary turbidite formations [1, 2].
Non-marine fossils are rarely seen in the gritstone rock, but marine fossils can be found in the shale layers of the turbidites, showing that the area was once close to or beneath the sea.
These megablocks are aligned along Variscan thrust faults and lie between different folded and faulted massifs of Culmian (Mississippian flysch) turbidites (Hladil et al., 1999; Babek et al., 2006).
The deep-water turbidites and shallow-water carbonates of Morrowan-Lower Atoka to the south of the fault are dominated by isoclinal folds and imbricate faults [10].
Among the topics are the character and significance of flood deposits in continental and marine environments, a case study of genetic indices in hyperpycnal systems in the Late Oligocene to Early Miocene merecure formation in Venezuela's Maturin Sub-basin, fluvial-derived turbidites in the Los Molles formation, ichnologic signatures of hyperpycnal flow deposits in Cretaceous river-dominated deltas in the Austral Basin of southern Argentina, and evidence of shelfal hyperpycnal deposition of Pliocene sandstones in the Oilbird Field on the southeast coast of Trinidad.
During a 2007 expedition to Sumatra, an OSU team looking for turbidites (gravel deposits that act as earthquake indicators) in deep-sea sediment cores found evidence of volcanic ash, which led to a parallel investigation of Sumatra's volcanic history
Sediment distribution is controlled by biogenic productivity, calcium carbonate dissolution, and sediment input from turbidites and ice rafting (Aksu and Piper, 1979; de Vernal et al., 1992).